Y. Haruyama

Charge state dependent energy loss of high velocity carbon ions in the charge state non-equilibrium region

Abstract Energy losses of high velocity bare H-like and He-like carbon ions passing through thin carbon foils were measured in the charge state non-equilibrium region. The mean energy losses for each charge state increased proportionally to the foil thickness and a clear charge state dependence was observed.

Charge state dependent energy loss of high velocity oxygen ions in the charge state non-equilibrium region

Mean energy losses of high velocity bare H-like, He-like and Li-like O ions in thin carbon foils were measured in the charge state non-equilibrium region and a clear charge state dependence was observed. The screening effect of bound projectile electrons on energy losses are deduced and compared with theoretical predictions.

Charge-changing contribution to energy loss of 32 MeV 3He+ in the charge state non-equilibrium region☆

Abstract Energy losses of 32 MeV 3 He ions by carbon foils were measured in the charge state non-equilibrium region. The mean energy losses exhibited an abrupt change as a functiion of the foil thickness around 40–50 μg/cm 2 . This behavior is quantitatively explained by considering the contribution from charge-changing collisions.

Energy loss of high velocity 6Li2+ ions in carbon foils in charge state non-equilibrium region

Abstract Mean energy losses of high velocity H-like Li ions in thin carbon foils were measured in the charge state non-equilibrium region. Owing to the screening effect of the bound electron, the fixed-charge stopping power for 6 Li 2+ was smaller than that for 6 Li 3+ . The projectile atomic number dependence of the fixed-charge stopping powers for H-like ions is discussed including our previous data of He, C and O ions with the same velocity. The present result is also compared with the theoretical prediction.

Single-, Double- and Triple-Electron Capture Cross Sections for Multicharged Slow Carbon Ions in H2, CH4, C2H6, C3H8 and CO2 Molecules

Cross sections have been measured for single, double and triple electron capture by C q + ( q =1–4) ions from H 2 , CH 4 , C 2 H 6 , C 3 H 8 and CO 2 molecules in the energy range of (1–20) q keV. The cross sections obtained here exhibit little dependence on the incident energy. Compared with the previous scaling laws, the present cross sections revealed a much stronger dependence on the first ionization potential of the molecules. For hydrocarbon molecules including H 2 all the cross sections show a remarkable linearity on the number of compositeatoms. The single electron capture cross sections σ q , q -1 are compared with the classical over barrier model and with the Olson model which was slighty modified so as to be applied to the molecular targets.

Measurement of absolute detection efficiencies of a microchannel plate using the charge transfer reaction

A new method for determining the absolute detection efficiencies of a microchannel plate (MCP) detector is presented. This method uses a charge transfer reaction and can be applied to determine not only the detection efficiencies for ions but also those for neutral atoms. The measurements were carried out for Ar+ and neutral rare gas atoms (Ne, Ar, Kr and Xe) in the 0.5?4.8?keV energy range. The detection efficiencies for all species increase with increasing impact energy and approach the open area ratio of the MCP used (about 50%). The measured detection efficiencies were found to scale with the Lindhard, Scharff and Schiott formula for electronic stopping power at keV energies.

Energy losses and straggling of light ions transmitted through thin carbon foils

Abstract The energy losses of 10 MeV/amu 3 He 2+,1+ , 6 Li 3+,2+ , 12 C 6+,5+,4+ and 16 O 8+,7+,6+,5+ ions passing through carbon foils of 5–110 μg/cm2 in thickness were measured with a high resolution magnetic spectrograph. The measurement was carried out for ions emerging from foils in the same charge state as the incident beam. The measured fixed-charge stopping powers have been reported in our previous papers. In this paper, the energy loss straggling of partially clothed ions in the charge-state nonequilibrium region is reported for the first time. A double peak structure in energy loss spectra of 3 He 1+ and 6 Li 2+ ions transmitted through carbon foils of 40–50 μg/cm2, which is due to charge changing contributions, was also described before. The present study shows that these contributions also bring about a characteristic behavior in the foil thickness dependence of the straggling values. For partially clothed C and O ions, a linear relation between the foil thickness and the straggling does not hold in the thicker foil region and the straggling exhibits an abrupt increase, although the double peak structure did not appear in the energy loss spectra. A Monte Carlo simulation taking account of the charge exchange can well reproduce the energy loss straggling of 3 He 1+ and 6 Li 2+ emerging from thicker foils.

Electron-loss cross-section measurement of 3He ions by the attenuation method

Abstract We have measured single-electron loss cross sections of 3 He 1+ ions for various solid targets such as C, Al, V, Cr, Cu, Ge, Nb, Ag, Sn and Au at 72 MeV by using the attenuation method. In this method residual 3 He 1+ fractions after charge-changing collisions were measured with a 3 He 1+ incident beam. Concentrations of contaminating atoms in the target were determined by an independent RBS measurement. It was found that surfaces of almost all the targets were covered with thin oxygen layers by which 3 He 1+ fractions were reduced by about 10%. Corrections of the observed loss cross sections are made for the surface oxygen layers.

Radiative lifetime measurement of the 1S0 metastable state of Kr2+ using an electrostatic ion trap

We measured the radiative lifetime of the 1S0 metastable state of Kr2+. This state dominantly decays to the 3P1 state via a magnetic dipole transition. The lifetime was determined by measuring emitted photons (350.5 nm) as a result of the 1S0 → 3P1 decay of Kr2+ stored in an electrostatic ion trap. The obtained radiative lifetime was 15.3 ± 0.9 ms, which agrees with the experimental value reported by Calamai and Johnson (1992 Phys. Rev. A 45 7792) within experimental error.

DISTRIBUTIONS OF ALUMINUM AND SILICON IN TEA LEAVES

Elemental distributions of Al, Si, P, S, K, Ca in tea leaves were measured using micro-beam PIXE. In mature tea leaf, aluminum localized eccentrically in the upper epidermis and silicon showed quite similar spatial distribution. It was found that the aluminum concentration and spatial distribution changeed with the growth period of the tea leaf. In younger leaves of two and four month, aluminum showed relatively low concentration compared with the matured one and distributed in mesophyll cell uniformly. In five month leaf, aluminum concentration became higher and the distribution began to localize in upper surface